Division-head propelling screen



Sept. 13, 1927. W. F MCMAHON mvzsxou HEAD PROPELLING scnmm 2 Sheets-Sheet 1 Filed March 14, 1927 Se t. 13 1927.

p w. F. M MAHON DIVISION HEAD PROPELLING SCREEN Filed M ch 14, 1927 2 Sheets-Sheet 2 Patented Sept. 13, 1927.

NKTED STATES ATENT OFFlCE.

DIVISION-HEAD PBOPELLING SCREEN.

Application filed March 14, 1827. Serialflo. 176,280.

This invention relates to a novel construction for propelling a material through a perforated screen that is adapted to keep a certain grinding media in its respective place 8 in a crushing or grinding mill, and has for its object improvements in devices for this.

purpose of the kind in which the rotary action of the mill shell is utilized as the motor medium in cooperation with the spiral or v 10 helical formation of the perforated screen to efiect positive delivery of the material through the erforations in the screen.

Another 0 ject is to provide a perforated screen that will have a spiral screw action on the material that comes in contact with t,

whereby the material is propelled through 1t.

A further object is to provide a perforated screen that will automatically prevent the perforations in it from'cloggin Heretofore it was thought t at the relative low eificiency of a grinding mill was mainly due to the grindin media therein, 1

' discovered by research t at the grinding media in all grinding mills is highly eflicient, and. that the low eflicien was directly due to the perforated screen in same, retarding the flow of the ground material from discharging out of the mill or from entering the adjacent compartment.

In other words, the function of a screen in a grindigg mill is mainly to keep the grindmg m ia in place in its 'respectlve compartment and at the same time allow all material that reaches it to plass through it to the next compartment in t e grinding mill.

Also the size mesh of the material discharged from a mill or compartment depends directly upon the length of the mill or compartment relative to the grinding media and the size of the material feed.

It should be noted that all material in a grinding mill'travels substantially in a set channel in the grin'din media and when said material has passed t rough thelength of the com artment upon reaching the screen should Ea ediately'passed throu' h the screen to prevent the retarding of t e incoming 7 material, therefore in all present screens depending upon'weight 'of the mass of the material to force the same through a fast revolving perforation, it suflices to say that if the material. was positively delivered through the perforations the latter would be most'eficient means.

Also the. entire body of ground material adjacent the said screen lays in a sector of the grinding media in one segment of the mill near its shell, hence by my'radial perforations it will be seen that each erforation will come in contact with the entlre body of ground material making thereby a highly eflicient discharge.

Technically speaking what governs the horsepower of the inding mill is the weight of the mill p us the weight of the grinding media and material in same and plus the weight of the screen, relative to the speed of the said mill. The screen in the mill plays but a small part in the horsepower formula outside of its weight, regardless of what type of screen it is but you can readily see that if all material that reaches it, is immediately passed through the said screen, you will get a higher roduction from the grlnding mill with su stantially the same horsepower than you would if the ground material was retarded from assing out of the mill and was continually lstributed over the in'ding media in' the mill. ith these and other objects in view, the mvention resides and consists in'the construction and novel combination and arrangement of parts hereinafter more fully described, and illustrated in the accom anying drawings, and pointed out in the c aims hereto aplpended, 1t being understood that various c anges in the form, proportion,

8128 and minor details of construction within the scope of the claims may be resorted to without departure from the spirit or sacrificing any of the advantages of the invention.

'Similar characters of reference denote like or corresponding parts throughout the several figures of the accompanying drawmgs formin a part of this speclfication, and upon w 'ch,

Figure 1 is an end view of my division head propeller screen, taken onthe grinding media side of the screen, showing two segments of the screen in position, with three se ents omitted, these omitted segments will be similar to the two segmentsshown, also showing the general formation of the semen supporting arms. In

Fig. 2, is a sectional e evation at 0-0 of re 1, and Fi' re 3.

is a on view of the division head P e n taken on the u: a and -8, showing the rearwardly inclined perview is on a third angle projection relative to Figure 5.

Fig. 7, is the other side view of Figure 5, this view is also on a third angle projection, relative to Figure 5.

Fig. 8, is a detailed plan view of a perfora-ted screen segment, showing the radial perforations.

Fig. 9, is a section at M or Figure forations.

Fig. 10, is a detailed plan view of the com bined spout and litter.

Fig. 11, is a section at e-e of Figure 10 Referring in detail. to the characters of reference marked upon the drawings, 1 represents the shell of grinding mill that encases the shell liners 2 which are provided as a wearing plate for the grinding media in the mill. As the oonstructlon and operating principle of a grinding mill is well known ll will only describe the parts pertaining to 111 tion would e superfluous. ile this division head screen is substantially the same construction as the propeller screen shown in my copending application Serial Numhen. 146,262, and filed on or about the 4th day of November 1926, this resent a plication contains a more speci c speci cation and illustrations and pertains to the specific construction of a division head -'propeller screen as applied to compartment or compel) mills, which is the commercial name of this particular type of grinding mill.

This compartment grindlng mill may contain several respective compartments for the purpose of each compartment containing 'a specific grinding media. In my application Serial Number 146,262, I have shown a typical screen for ball mills and tube mills. A compartment or compeb mill is a combined ball and tube mill, the division head screen (all illustrated in the ap ended drawings herewith is the division head between the said ball and tube mill compartments.

ll desireto plainly note at this time that my propeller screen is not provided for the purpose of actuating the grinding media to increase the grinding action of same upon the material being ground,-but the said propeller screen is provided to propel all material that comes in contact with it through the perforations initemploying the same invention as all other descrip-- principle as a propeller blade on water, or a similar action as a spiral screw conve or.

To accomplish this said propeller b ado action upon the material, ll provide acoustruction similar to a spolred'wheel g an inner hub 3, arms orspokes a, and an outer rim 5. R

This said wheel construction forms cir= cular ring sector space 6 between each l and in this circular ring sector space 1 Fe place my perforated screen 7 on an inclin tion, as clearly shown in Figure 4. The entire screen 7 being inclined toward the direction of rotation of the shell 1 as indicated in the several figures. of the illustrations to by the arrows.

While the screen 7 is inclined in horizontal section toward the direction of rotation of the shell 1, it is also inclined in an outer direction from the hub 3 toward these rim 5. To efi'ect these said inclinations ll provide a supporting lug 8, which. will be practically level on one side of the arm a and an inclined supporting lug 9 on the opposite side of the arm 4h The arm 1 to proper being substantially vertical to allow a general verticalsupport for the entire di vision head.

By referring to Figures 5, 6 and 7 will beseen the general construction of each arm, 655 which will contain an inner hub 10, that contains a groove 11 for the lifter 12. Alsothere are outer dispdsed rim supports 13 which will be inclined to suit the inclinations of the screen 7. Holes 14 are provided for bolts 15 no will be seen by referring to Figures 10 and- 11, and lifter 12 is provided to act as a spacer roe between the arm 4: and the back plates 16' and 17. It has a hub 18 formed into a spout 19 and an outward disposed portion 20 thatwill contain the two holes 21 for the bolts 15. Tl1lS litter 12 actuates the material that lilo" has passed through the screen 7 to the dis-,1 charge opening 22, and forms a discharge space 23 between the back plates 16 and 17 Y and the screens 7.

The back plates 16and 17' are formed the 11 shape of circular ring sectors, the outer. plate 16 having a groove :24 to mesh with the inner plate 17. In this particular construction l have shown these back plates separated at the center of the lifter 12. It is at this joint 25 ll place my holding bolts 15.

To prevent Wear on the boltlheads 26 these heads 26 are set into the plates. The inner plate 17 containing the discharge opening 22 is held in place by it bearing onto the lifters 12 and by means of the bolts 15, also by. the fact-that the plates bear against each at the said joint 25. It is to be noted that the outer plate 16 bears onto plate 17 and is held in place by the shell liners 2.

'through the perforations in it.

It may be well to state at this time that the entire division head is held in place in the grinding mill by the shell liners 2, an adjusting liner 27 cooperates with the said shell liners 2 and provides a take up means at the assembly.

Bolt 28 fastens the several arm segments with the several lifters 12. While I' have shown but one bolt performing this said function, several bolts may be provided to do this work if it is so desired.

The outer rim 5 forms the connecting link between the arms 4 and contains an inclined groove 30 so arranged as to support the screen 7, it also contains an outward disposed portion 29 that serves asa spacer between the screen 7 and the plate 16. This portion 29 tends to hold the screen 7 in place in relation to the arms 4: and plates 16 and shell liners 2.

The screen 7 is substantially a circular ring sector comprisin a series of radial perforations 31 inclined rearwardly relative to the movement of the screen. It should be noted that these said perforations do not have to be inclined toward the direction of the movement of the screen rearwardly to get a spiral action on the material. But any form of perforation put into this screen will have a substantially propeller action on the material as this entire screen is inclined toward the direction of the movement of the said grindin mill. However a rearwardly inclined per oration is preferable because it tends to prevent the perforations from clogging. The screen 7 is held stationary in place in the division head by supporting lugs 8 and 9 in the arms 4, and by the. rim 5 on one side. On the opposite side the shell liner 27 holds it in place together with a plate 32 that has a bolted connection with thearm 4.

It should be noted that in this novel construction each screen 7 or circular ring sector is separated by an arm 4 making thereby an independent propeller blade of each sector. The general construction of the assembled sectors or screens being of a so called sawtooth formation each screen being independent of theother and sloped toward the direction of the movement of the mill. So that regardless of what the shape of the perforation is therein, the tendency of cachindividual screen will be to function as a propeller blade and positively effect the delivery of all material that comes in contact with it However a radial perforation is in my mind preferablebecause each perforation will be swept th iilmgh the entire body of material in the m1 Having thus described my invention, what I claim and desire to secure by Letters Patent is, y

1. In a grinding mill, the combination with a rotary shell, of a division head comprising a series of separating screens inclined transversally between two radii.

2. In a grinding mill, the-combination with a rotary shell, of a division head comprising a series of separating screens inclined transversally between two*radii and being so formed as to cause a positive passage of the material therethrou h. i

3. In a grinding mill, the combination with a rotary shell, of a division head comprising a series of separating screens inclined transversally between two radii and being so formed as to cause a positive passage of the material therethrough, spaced means separatin the screens.

4. In a grin ing mill, the combination with a rotary shell, of a division head comprising a series of separating screens inclined transversally between two radii and being so formed as to insure a positive delivery movement of the ground material.

5. In a grinding mill, the .combination with a rotary shell, of a division head comprising a series of separating sreens being so formed as to insure a positive delivery movement of the ground material therethrough, spaced means between the said screens, and means for securing the separat ing screens to the first named means.

6. Ina grinding mill the combination with a rota shell of a division head comprising a series of separating screens inclined transversally between two radii and being so formed as to insure a positive delivery movement of the ground material therethrough, spaced means separating the said screens, and means for securing the said separating screens stationary with the said rotary shell.

7. In a grinding mill, the combination with a rotary shell, of a division head comprising a series of separating screens inclined transversally between two radii and being so formed as to cause a positive passage of the materialtherethrough, spaced arms separating the screens, an inner hub. an outer ring, said arms forming connecting means between the hub and ring. a partition wall comprising a discharge opening. spaced separators forming a spout between the wall and arms, and means for securing the said separating screens stationary relative to the said rotary shell.

8. In a grinding mill, the combination with a rotary shell, of a division head comprising a series of separating screens in clined transversally between two radii and being so formed as to cause a positive delivery movement of the material therethrough, a partition wall comprising a dis charge opening, a delivery space between the separating screens and partition wall, and means for securing the separating screens and partition wall stationary relative to the said rotary shell.

9. In a grinding mill, the combination with a rotary shell, of a division head comprising a series of separating screens inclined transversely between two radii and 5 being so formed so as to cause a positive delivery movement of the material there through, spaced means separating the separating screens, a partition wall comprising a eeaiae discharge spout, a delivery space 31 'ween the separating screens and part tion -111E, and 1 means for securing the (li head stationary relative to the lOi w ll" Signed at Riverside, in U lll'li) of Riverside and State of California'thi- 8th day of March 1927. 

